In order to ensure the interoperability among object representations and even between different object systems that uses the same representation. In this context we need to define the HOW and REPR API, this is the SMOP OO API that allows representations to be interchanged, and custom BUILD methods to be written.

REPR API

This is SMOP specific, and it isn't part of the standard Perl 6, however, this is how different representations can coexist in SMOP. This only operates in the specific object, it doesn't look to any of the superclasses, that might even have a different representation.